Camera behavior ..broken?
I have a solution, but i still do not know what caused this problem. 

When i create an extra Screen Layout (opened the '3D view Full' and pressed the '+' to make it a new one, named it 'Default_2'), and reconstructed my preferred screenview, the problem is gone. The original Default screenview is still broken. Dunno why. 

Found this solution in another topic: 

Original posted solution to the same problem